ABSTRACT The long-term goal of this project is to improve pain management for older adults with knee osteoarthritis (OA). Knee OA is one of the most common pain conditions among people over 45, and the management of OA pain is challenging because the pain is only partially responsive to existing pharmacological approaches, which are often associated with adverse effects. Also, knee OA pain is characterized by increased pain-related brain activation, possibly explaining the limited success of existing peripherally based treatments that target the pain locally in the area of the knee. Therefore, there is growing interest in interventions targeting brain function for this population. One promising treatment is noninvasive transcranial direct current stimulation (tDCS) with the anode over the primary motor cortex (M1) and the cathode over the contralateral supraorbital area (SO) as it can change brain activity in a noninvasive, painless, and safe way. tDCS falls under the category described by the FDA as a ?non-significant risk? device. Recent studies suggest that clinic-based M1-SO applied tDCS has promising efficacy for managing chronic pain. However, no investigator to date has examined the effect of the self-administered home-based tDCS on clinical pain. Recent technological advances have increased the portability of tDCS, which creates the potential for home use with real-time monitoring through a secure video conferencing platform of stimulation delivered through electrodes mounted on custom single position headgear to ensure fidelity of treatment localization. The proposed study directly addresses this gap in the literature by investigating the effects of self-administered, remotely supervised M1-SO applied tDCS at home in 120 older adults with knee OA pain using an experimenter- and participant-blinded, randomized, sham-controlled, phase II parallel group (1:1 for two groups) design. The first aim of this study is to determine the effects of self- administered M1-SO applied tDCS on clinical pain intensity in older adults with symptomatic knee OA. The second aim is to determine the effects of self-administered M1-SO applied tDCS on pain-related cortical response in older adults with symptomatic knee OA. The third aim is to investigate the feasibility and acceptability of self-administered M1-SO applied tDCS in older adults with symptomatic knee OA. This study will provide definite insight into an exciting new modality of nonpharmacological pain self-management in that it will be extremely easy, safe, and noninvasive with minimal side effects.